From: Jesper Dangaard Brouer <brouer@redhat.com>
To: "Daniel T. Lee" <danieltimlee@gmail.com>
Cc: "David S . Miller" <davem@davemloft.net>,
netdev@vger.kernel.org, brouer@redhat.com
Subject: Re: [v2 2/3] samples: pktgen: add helper functions for IP(v4/v6) CIDR parsing
Date: Fri, 13 Sep 2019 14:43:05 +0200 [thread overview]
Message-ID: <20190913144305.4bf38c04@carbon> (raw)
In-Reply-To: <20190911184807.21770-2-danieltimlee@gmail.com>
On Thu, 12 Sep 2019 03:48:06 +0900
"Daniel T. Lee" <danieltimlee@gmail.com> wrote:
> This commit adds CIDR parsing and IP validate helper function to parse
> single IP or range of IP with CIDR. (e.g. 198.18.0.0/15)
>
> Helpers will be used in prior to set target address in samples/pktgen.
>
> Signed-off-by: Daniel T. Lee <danieltimlee@gmail.com>
> ---
> samples/pktgen/functions.sh | 122 ++++++++++++++++++++++++++++++++++++
> 1 file changed, 122 insertions(+)
>
> diff --git a/samples/pktgen/functions.sh b/samples/pktgen/functions.sh
> index 4af4046d71be..8be5a6b6c097 100644
[...]
> +# Given a single IP(v4/v6) or CIDR, return minimum and maximum IP addr.
> +function parse_addr()
> +{
> + # check function is called with (funcname)6
> + [[ ${FUNCNAME[1]: -1} == 6 ]] && local IP6=6
> + local bitlen=$[ IP6 ? 128 : 32 ]
> + local octet=$[ IP6 ? 16 : 8 ]
> +
> + local addr=$1
> + local net prefix
> + local min_ip max_ip
> +
> + IFS='/' read net prefix <<< $addr
> + [[ $IP6 ]] && net=$(extend_addr6 $net)
> + validate_addr$IP6 $net
> +
> + if [[ $prefix -gt $bitlen ]]; then
> + err 5 "Invalid prefix: $prefix"
> + elif [[ -z $prefix ]]; then
> + min_ip=$net
> + max_ip=$net
> + else
> + # defining array for converting Decimal 2 Binary
> + # 00000000 00000001 00000010 00000011 00000100 ...
> + local d2b='{0..1}{0..1}{0..1}{0..1}{0..1}{0..1}{0..1}{0..1}'
> + [[ $IP6 ]] && d2b+=$d2b
> + eval local D2B=($d2b)
I must say this is a rather cool shell/bash trick to use an array for
converting decimal numbers into binary.
> +
> + local shift=$[ bitlen-prefix ]
Using a variable named 'shift' is slightly problematic for shell/bash
code. It works, but it is just confusing.
> + local min_mask max_mask
> + local min max
> + local ip_bit
> + local ip sep
> +
> + # set separator for each IP(v4/v6)
> + [[ $IP6 ]] && sep=: || sep=.
> + IFS=$sep read -ra ip <<< $net
> +
> + min_mask="$(printf '1%.s' $(seq $prefix))$(printf '0%.s' $(seq $shift))"
> + max_mask="$(printf '0%.s' $(seq $prefix))$(printf '1%.s' $(seq $shift))"
Also a surprising shell trick to get binary numbers out of a prefix number.
> +
> + # calculate min/max ip with &,| operator
> + for i in "${!ip[@]}"; do
> + digit=$[ IP6 ? 16#${ip[$i]} : ${ip[$i]} ]
> + ip_bit=${D2B[$digit]}
> +
> + idx=$[ octet*i ]
> + min[$i]=$[ 2#$ip_bit & 2#${min_mask:$idx:$octet} ]
> + max[$i]=$[ 2#$ip_bit | 2#${max_mask:$idx:$octet} ]
> + [[ $IP6 ]] && { min[$i]=$(printf '%X' ${min[$i]});
> + max[$i]=$(printf '%X' ${max[$i]}); }
> + done
> +
> + min_ip=$(IFS=$sep; echo "${min[*]}")
> + max_ip=$(IFS=$sep; echo "${max[*]}")
> + fi
> +
> + echo $min_ip $max_ip
> +}
If you just fix the variable name 'shift' to something else, then I'm
happy with this patch.
Again, I'm very impressed with your shell/bash skills, I were certainly
challenged when reviewing this :-)
--
Best regards,
Jesper Dangaard Brouer
MSc.CS, Principal Kernel Engineer at Red Hat
LinkedIn: http://www.linkedin.com/in/brouer
next prev parent reply other threads:[~2019-09-13 12:43 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-09-11 18:48 [v2 1/3] samples: pktgen: make variable consistent with option Daniel T. Lee
2019-09-11 18:48 ` [v2 2/3] samples: pktgen: add helper functions for IP(v4/v6) CIDR parsing Daniel T. Lee
2019-09-12 15:59 ` Jesper Dangaard Brouer
2019-09-12 17:53 ` Daniel T. Lee
2019-09-13 12:32 ` Jesper Dangaard Brouer
2019-09-13 12:43 ` Jesper Dangaard Brouer [this message]
2019-09-14 15:02 ` Daniel T. Lee
2019-09-11 18:48 ` [v2 3/3] samples: pktgen: allow to specify destination IP range (CIDR) Daniel T. Lee
2019-09-13 12:31 ` Jesper Dangaard Brouer
2019-09-13 12:37 ` Toke Høiland-Jørgensen
2019-09-14 14:51 ` Daniel T. Lee
2019-09-13 12:04 ` [v2 1/3] samples: pktgen: make variable consistent with option Jesper Dangaard Brouer
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